Microbes Discovered Thriving in Deepest Oceanic Trench on Earth

In the depths of the darkest parts of the ocean, massive amounts of pressure, cold temperatures and low oxygen make habitation difficult for most creatures. Yet now, scientists have discovered an abundance of life in the deepest location in the Pacific Ocean--the Mariana Trench.

Published in the journal Nature Geosciences, the findings reveal that small microbes can cope with the hostile conditions located at the bottom of the trench, seven miles beneath the Pacific Ocean. The discovery was surprising considering the low oxygen content and the harsh environment at these depths.

In 2010, the researchers sent an unmanned submersible down into the trench where it collected samples of the murky sediment which makes up much of the sea floor. The pressures there were almost 1100 times greater than at the surface.

The scientists then examined the samples that were taken, measuring the levels of oxygen. Surprisingly, they found a large number of microbes in the samples--single-celled organisms that consumed oxygen. Perhaps more interesting, though, was the fact that these organisms were twice as active at the bottom of the trench than they were at a nearby site located a mere four miles beneath the surface of the ocean.

So what do these organisms eat? The scientists found that they feast on a supply of dead plants and creatures that slowly drift downward from the sea surface. The decomposing matter eventually becomes trapped within the steep walls of the trench and becomes food for the microbes.

"The amount of food down there and also the relative freshness of the material is surprisingly high--it seems to be surprisingly nutritious," said Robert Turnewitsch, one of the authors of the paper, in an interview with BBC News.

In fact, the level of decaying material found at the site was so high it suggested that the Mariana Trench, located in the Hadal zone of the ocean, may play an integral role in the carbon cycle. The trench could possibly be a key part in regulating the planet's climate.

The findings show that not only are there species that can survive high pressures and low temperatures, but also reveal that the Hadal trenches could influence the removal of carbon from the ocean and the overlying atmosphere. Yet more research still needs to be conducted on how effective these microbes are at breaking down organic material.